Stimulation leads, sensing leads, and active devices including power supplies or electrodes need to be predictably and securely attached to targeted biological tissue to provide proper therapy. Some existing assemblies and methods to provide attachment for these devices are large, over-penetrate tissue, or generally irritate the tissue to which they are attached, resulting in adversely affected sensing or stimulation. Therefore, there is a need for new and improved fixation assemblies for implantable medical devices.